DESCRIPTION: This proposal describes an epidemiologic study designed to examine the association between the incidence of IPF and potential etiologic agents. Specifically, the investigators will: (1) identify all incident cases of idiopathic pulmonary fibrosis referred to the University of Washington and affiliated hospitals, (2) identify age-, race-, and gender-matched controls from the practices of the referring physicians, (3) administer a standardized questionnaire dealing with occupational and environmental exposures to the cases and controls, (4) classify the exposure data into categories, and (5) estimate the relative risks and exposure response associations for exposure categories, specific exposures, and idiopathic pulmonary fibrosis.